Picking up is one thing, getting the signal back from the phone with it's small antenna and low power transmitter seems problematic. But perhaps they have solve

Picking up is one thing, getting the signal back from the phone with it's small antenna and low power transmitter seems problematic. But perhaps they have solved that somehow. At those distances, I am guessing the uplink would be very limited due to this. Keep in mind, that cellular carriers over time want the signal of each phone reduced. The reason is that for cellular, to get the capacity up, you want to have more cell site, each site re-uses the same spectrum of the site next to it, so if all the phones had higher power they would all be interfering with each other. They just are not designed to go those kinds of distances. Most cell radii is in the 1 - 5 mile type of range usually. Again, for capacity reasons. In the early days when there were fewer towers spaced farther apart the phones had more power (remember the old "brick phones").